Current Research

1. Electron Collision Spectroscopy
    High-Resolution Fast-Electron Energy Loss Spectroscopy (EELS)： In this method, monoenergetic electron beam of 1-5 keV is produced and collides atoms and molecules. The excitation energy of atom or molecule can be determined by measuring the difference of energies of the incident and scattered electrons. Then the differential cross section of a definite state can be determined by the angular distribution of its intensity. From the measured dynamic parameters, the information of wave functions of initial and final states in the momentum space can be revealed. Furthermore, this method has the merits to measure and assign the dipole-forbidden transition since it is free from the electric dipole selection rule due to the fact that there is momentum transfer in the collision processes, i.e., the transferred momentum is decoupled to the transferred energy while it is coupled in the photoabsorption process. Therefore, the electron energy loss spectroscopy provides the information of a new dimension-momentum space, and it can give a complete description of the excitation structure and dynamics of atoms and molecules.

2. X-ray Scattering Spectroscopy
    Inelastic X-ray Scatting Spectroscopy (IXS)：Using advanced synchrotron radiation light sources all around the world, such as SPring-8 in Japan and Shanghai Synchrotron Radiation Facility, we carried out the investigations of the inelastic X-ray spectroscopy of atoms and molecules. Similarly, the excitation energy of atom or molecule can be determined by measuring the difference of energies of the incident and scattered photons. The differential cross section of a definite state can be determined by the angular distribution of scattered photon’s intensity. Then the squared form factor of a definite transition can be converted from the measured differential cross sections. From the measured dynamic parameters, the information of wave functions of initial and final states in the momentum space can be revealed. Since inelastic X-ray scattering is a very clear spectroscopic technique, the accurate dynamic parameters determined by IXS can be served as experimental benchmark data to test theoretical models and calculational codes strictly.

3. Fine Spectroscopy of Dielectronic Recombination for heavy ions
    Fine Spectroscopy of Dielectronic Recombination：By using merged beams and electron cooling technique, the accurate measurements of high-resolution dielectronic recombination spectrum of highly charged ions can be determined, and the effects of relativity, QED, electronic correlation and isotope, as well as hyperfine structures of heavy ions can be revealed.